In the semiconductor industry, the dicing of wafers for separating semiconductor elements is often performed using laser dicing methods. In a laser dicing method, a laser is used to form scores on the surface of the wafer enabling separation of the semiconductors which are present on the wafer.
On the wafers the semiconductor elements are formed separated by cutting lanes, wherein the semiconductor elements are often arranged in a matrix configuration. Separating the individual semiconductor elements from the wafer is performed by forming scores in these cutting lanes, in between each of the semiconductor elements. In a matrix configuration, a plurality of parallel scores has to be formed in two different directions in order to separate the semiconductor elements from the wafer.
As will be understood, a continuous effort is made in the semiconductor industry to form as many as possible semiconductor elements on a single wafer. This will make the production process more efficient, and thereby reduce the production costs. The dimensions of the cutting lanes form an important parameter determining the amount of semiconductor elements that can be formed on a single wafer. Ideally, the cutting lanes should be as narrow as possible in order to optimize the portion of the surface of the wafer available for forming semiconductor elements.
The cutting lanes present on the wafer are broader than the scores to be formed in order to form a buffer that may compensate for inaccuracies of the dicing method. These inaccuracies may be caused, for example, by inaccurate placement of the wafer relative to the laser beam, such that the score is formed not exactly where it was intended to be formed. Small variations in the placement of the substrate relative to the laser beam is compensated by the cutting allowing for such inaccuracies. However, as mentioned above, the disadvantage of broad cutting lanes is that a smaller portion of the wafer surface is available for forming semiconductor elements.
As will be understood, the laser dicing method should be as efficient as possible in order to increase the through put of wafers to be cut using the dicing method. This may for instance be achieved by using a plurality of laser beams such that a number of scores can be formed simultaneously by the plurality of beams. Ideally, each of the laser beams used for cutting the wafer has similar properties e.g. (with respect to intensity, intensity profile and pulse rate), such that the simultaneously formed scores have similar properties with respect to depths, broadness, thermal side effects etc. This is not straight forward, since the properties of each laser beam used are largely determined by its laser source and the optical system used to guide the beam to a surface.